diff --git a/DIKit.xcodeproj/project.pbxproj b/DIKit.xcodeproj/project.pbxproj
index 2ee5841..1c605f2 100644
--- a/DIKit.xcodeproj/project.pbxproj
+++ b/DIKit.xcodeproj/project.pbxproj
@@ -722,6 +722,7 @@
 				);
 				PRODUCT_BUNDLE_IDENTIFIER = org.ishkawa.DIKit;
 				PRODUCT_NAME = "$(TARGET_NAME:c99extidentifier)";
+				SDKROOT = macosx;
 				SKIP_INSTALL = YES;
 				SUPPORTED_PLATFORMS = "macosx iphonesimulator iphoneos watchos watchsimulator appletvos appletvsimulator";
 				SWIFT_OPTIMIZATION_LEVEL = "-Onone";
@@ -750,6 +751,7 @@
 				);
 				PRODUCT_BUNDLE_IDENTIFIER = org.ishkawa.DIKit;
 				PRODUCT_NAME = "$(TARGET_NAME:c99extidentifier)";
+				SDKROOT = macosx;
 				SKIP_INSTALL = YES;
 				SUPPORTED_PLATFORMS = "macosx iphonesimulator iphoneos watchos watchsimulator appletvos appletvsimulator";
 				SWIFT_VERSION = 4.2;